Alginate-like exopolysaccharides extracted from different waste sludges exhibit varying physicochemical and material properties

Zahid Ur Rehman; Masoud Ghaani; Ahmed Y A Mohamed; John Gallagher; Pascal E Saikaly; Muhammad Ali

doi:10.3389/fmicb.2024.1493782

Alginate-like exopolysaccharides extracted from different waste sludges exhibit varying physicochemical and material properties

Front Microbiol. 2024 Nov 5:15:1493782. doi: 10.3389/fmicb.2024.1493782. eCollection 2024.

Authors

Zahid Ur Rehman^#^{1

2}, Masoud Ghaani^#³, Ahmed Y A Mohamed³, John Gallagher^{3

4}, Pascal E Saikaly¹, Muhammad Ali³

Affiliations

¹ Biological and Environmental Science and Engineering Division, Water Desalination and Reuse Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
² Research and Analytical Services Department, Saudi. Aramco, Dhahran, Saudi Arabia.
³ Department of Civil, Structural and Environmental Engineering, Trinity College Dublin, The University of Dublin College Green, Dublin, Ireland.
⁴ TrinityHaus Trinity Research Centre, Trinity College Dublin, Dublin, Ireland.

^# Contributed equally.

Abstract

This study examined the influence of different wastewater treatment processes on the physicochemical properties of Alginate-Like Exopolymers (ALE) extracted from waste sludge. Sludge samples were collected from wastewater treatment plants (WWTPs) processing both combined industrial and domestic wastewater, as well as domestic wastewater alone. Among the processes studied, aerobic granular sludge (AGS) produced the highest ALE yield (352 ± 50 mg/g-VS_sludge), significantly exceeding that from membrane bioreactor (170 ± 41 mg/g-VS_sludge) and conventional activated sludge (<130 mg/g-VS_sludge). AGS-derived ALE also had the highest uronic acid content (224 ± 14.5 mg/g-VS_sludge), with mannuronic acids playing a critical role in enhancing hydrogel cohesion and stability. The results showed that the distinct microbial consortium in the AGS system, including the presence of Pseudomonas alcaligenes, was strongly associated with increased ALE production. This establishes a novel link between microbial community composition and ALE yield. These insights are crucial for optimizing resource recovery in AGS systems and underscore the potential of ALE for various industrial applications.

Keywords: activated sludge; aerobic granular sludge; alginate-like exopolysaccharides; membrane bioreactor; physicochemical characterization; wastewater.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study was supported by the Near Term Grand Challenge Funding Program (REI/1/4254-01-01) at King Abdullah University of Science and Technology (KAUST), Irish Research Council (IRC) (GOIPD/2023/1290), and Science Foundation Ireland (SFI) National Challenge Fund Program (22/NCF/TF/10978).